Method and apparatus for ESWL filming

ABSTRACT

A method and apparatus are disclosed for performing in-bath filming during extracorporeal shock wave lithotripsy. The device has a holder for slidably receiving a film cassette and a grid therein. The holder has means for slidably mounting the holder on the image intensifier portion of an x-ray fluoroscope so that forces on the front of the holder can be transferred to pressure sensing means on the intensifier. The holder is constructed in a water-tight manner so that the film contained in the holder may be delivered beneath the level of water in the bath adjacent the abdomen of the patient in the bath. An inflatable bladder is provided on the outside of the holder to displace water from the area between the holder and the abdomen to prevent absorption and scattering of the x-rays by water in the area between the holder and the patient&#39;s abdomen.

This application is a continuation of U.S. patent application Ser. No.813,394, now U.S. Pat. No. 4,665,543, filed Dec. 23, 1985.

TECHNICAL FIELD

The invention relates to methods and apparatus for making x-ray films.More specifically, the invention relates to a method and apparatusforming x-ray images during extracorporeal shock wave lithotripsy.

BACKGROUND OF THE ART

The recent development of extracorporeal shock wave lithotripsy (ESWL)has greatly reduced the necessity for performing surgery to removecalculi from renal tissue. The occurrence of calculi in tissuefrequently occurs in the form of what is commonly known as kidneystones. ESWL has provided a method for fragmenting the calculi withpressure waves so that the stones may be passed in urine without resortto surgery in the majority of cases.

During ESWL treatment the patient is immersed and stabilized in a tubfilled with demineralized and degassed warm water. Pressure waves aretransmitted through the water and focused on the calculi to pulverizethe calculi into particles having the size of sand grains. x-rayfluoroscopes are used to aim the electrodes which generate the pressurewaves in the water bath. Typically, the x-ray sources are placed beneaththe tub while the fluoroscope image intensifiers are placed in directcontact with the abdomen of the patient at the axial position of thex-ray image. Video monitors provide a picture of the calculi whichallows the focus of the pressure waves to be precisely positioned. Aforward head portion of the image intensifier penetrates the top levelof the water and touches the abdomen of the patient.

Although this procedure has been highly effective for reducing the needfor surgery it has been found that the images provided by thefluoroscopes (two fluoroscopes are usually provided to get more precisepositioning of the shock waves) have insufficient resolution to providegood aiming of the shock wave generator electrodes once the calculi hasbeen broken down into smaller fragments. Moreover, the resolution isinsufficient to access the size of the calculi fragments and whetherfurther exposure to the shock waves is necessary. Presently patients areremoved from the water bath after the initial treatment and taken to anx-ray facility to provide high resolution x-ray images of the treatedtissue. If further treatment is required, the patient is then reinsertedinto the water bath and again immobilized therein. The fluoroscopeimages are compared to the x-ray images so that the shock waves can beprecisely focused on the remaining particles.

This procedure is extremely inefficient and expensive and results inunder utilization of the machines. Presently, cost of these machines areon the order of $1.7 million dollars. Moreover, patients receive moreshocks than would be necessary if the location and size of the fragmentscould be more precisely determined without removing the patient from thebath. Thus, a need exists for producing high resolution images duringESWL which does not require removal of the patient from the water bath.Furthermore, more precise aiming of the electrode pressure wavegenerators could reduce the number of shocks which a patient would haveto receive thereby decreasing hematuria and renal morbidity (blood inthe urine and kidney tissue damage).

DISCLOSURE OF THE INVENTION

It is therefor an object of the invention to provide a method andapparatus for producing in-bath x-ray films to provide a high resolutionx-ray image of the treated area without removing the patient from thewater bath.

Basically, the invention achieves this object and other objects andadvantages which will become apparent from the description below byproviding a x-ray film cassette holder which is mountable on the imageintensifier portion of an x-ray fluoroscope. The film holder is providedwith means for displacing water between the film holder and thepatient's abdomen so that absorption and scattering of the x-rays bywater is minimized.

In the preferred embodiment, the holder is slidably mounted on the endof the intensifier so that the intensifier may be driven towards thepatient's abdomen in the conventional manner by an electric motorwithout defeating the pressure sensing feature of such intensifierswhich cuts off the electric drive once the end of the intensifier hascontacted the abdomen. In this way, the sliding feature of the holdertransfers pressure from the contact between the patient's abdomen andthe holder to the extending portion of the intensifier to activate thepressure sensitive switch. The holder incorporates means for maintaininga film cassette and a grid in a proper orientation to the x-rays and ina water-tight environment so that the film and grid can be immersedbeneath the level of the water in the bath.

The invention is most advantageous in that high resolution x-ray filmscan be produced without removing the patient from the water therebyimproving the accuracy and efficiency of the treatment and decreasingundesirable side effects.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric view of a portion of a water bath wall, aconventional fluoroscope image intensifier and the fluoroscopeattachment of the present invention.

FIG. 2 is an enlarged isometric view of the holder of FIG. 1 lookinggenerally in the direction of arrows 2--2 of FIG. 1.

FIG. 3 is a top plan view of the fluoroscope attachment of FIG. 1.

FIG. 4 is a sectional view taken generally along lines 4--4 of FIG. 1.

BEST MODE FOR CARRYING OUT THE INVENTION

In FIG. 1, a fluoroscope attachment for holding a grid and film cassettefor in-bath filming during extracorporeal shock wave lithotripsy (ESWL)is generally indicated by reference numeral 10. The attachment isslidably mountable to the outer housing 12 of an image intensifier 14 ofa fluoroscope. The image intensifier 14 is connected by an arm 16 to asidewall portion 20 of an immersion tub for ESWL treatment. Theremainder of the ESWL machine is not shown but is entirely conventionaland well known by those skilled in the art.

The image intensifier 14 of the fluoroscope illustrated in FIG. 1 isfrom a Dornier ESWL manufactured by Dornier System GmbH, Friedrichafen,West Germany. In this instrument, the patient is submerged in ademineralized water bath and immobilized in the bath using a suspendedchair arrangement (not shown). The patient is strapped into the chair sothat the kidneys can be precisely located while in the bath. Underwaterelectrodes (not shown) produce pressure waves which pass through thewater and the patient's soft tisue until calculi (kidney stones) areencountered. The calculi absorb the energy transmitted by the waves andshatter due to the brittle nature of the calculi. After repeated shockwaves (up to 2000) sufficient fragmentation of the calculi occurs sothat the fragments may be passed through the urine.

The image intensifier 14 transmits a video signal through a cable 22 toa video monitor (not shown). In the conventional machine asmanufactured, the image on the monitor is used to focus the pressurewaves on the calculi. The fluoroscopic image produced on the videomonitor, however, has insufficient resolution to allow accurate aimingof the shock waves once the calculi has been broken up into smallerfragments. Moreover, the resolution is insufficient to access the sizeof the calculi fragments and whether further exposure to the shock wavesis necessary. In the past, the patients have been typically removed fromthe water bath to an x-ray facility where x-ray films of the treatedarea are taken. The patient is then reinserted into the bath for furthertreatment. The physician compares the fluoroscopic images received bythe image intensifier (two are typically provided to provide accuratefocusing of the beam at a position defined by two axis) to the x-rayfilms to correctly identify the position of fragmented calculi forfurther fragmentation.

The fluoroscopic attachment 10 of the present invention provides anapparatus and method for producing high resolution x-ray films of therelevant abdominal area without removing the patient from the bath. Anumber of advantages accrue from such in-bath filming including reducingthe number of shocks necessary for successful treatment, potentiallydecreasing renal morbidity, reducing the number of electrodes necessaryper patient treatment, decreasing the time required for treatment,eliminating the preparation time otherwise necessary when the patient isreinserted in the bath for further treatment, and decreasing repeat ESWLtreatment, all of which reduce the overall cost of the procedure. Themethod of in-bath filming which has been developed can be quickly andeasily done during the procedure with a total required time of onlyabout three to five minutes. The quality of the film obtained isexcellent and allows determination of the completeness of fragmentation.The quality of x-ray images obtained are superior to that attainablewith the currently available multi-format images recorded from the videomonitors.

As shown in the remaining figures, the fluoroscope attachment 10 has aholder 24 which is adapted to receive a grid 26 (80 cm focus, 8:1, 34lines per centimeter) and a 24×24 centimeter film cassette 28 with Lanexregular screens and OG film (Kodak Company). The grid and film cassetteare shown in FIG. 4 removably positioned in a grid receptacle 30 and afilm receptacle 32, of the holder 24. The holder 24 has a front wall 34constructed from a substantially x-ray transparent plate material whichis maintained in a spaced apart substantially parallel relation from asimilarly x-ray transparent back wall 36. The holder has left and rightsidewalls 38 and 40, respectively, and a bottom 44. The front wall, backwall, sidewalls, and bottom are constructed of a waterproof material anddefine a watertight container with an open upper end. The receptacles 30and 32 formed within the holder 24 are defined by the front and backwalls, sidewall and bottom, and have an open upper end sized to acceptthe film cassette and grid therethrough. Projections 48 extend inwardlyfrom the sidewalls to further define the grid and film receptacles 30and 32, and hold the grid and film in proper position within the holderrelative to each other.

Attach means are provided for slidably mounting the holder 24 to theouter housing 12 of the image intensifier 14. It is noted that the outerhousing is manufactured from a waterproof material and provides a sealto prevent the invasion of water into the interior of the imageintensifier. The attachment means provided hold the film cassettesubstantially perpendicular to the longitudinal axis of the imageintensifier 14, and hence substantially perpendicular to the axis of thex-ray beam impinging upon the film cassette 28. Of course, thisorientation is parallel to the x-ray image focused on the intensifier.As such, an undistorted image is produced on the x-ray film.

In the preferred embodiment of the invention the attachment means arethree struts 50 which extend rearwardly from the back wall 36 of theholder 24 with a substantially perpendicular relationship thereto. Asshown in the figures, the three struts are circumferentially andradially spaced apart from one another sufficiently to closely acceptthe cylindrical outer housing 12 of the image intensifier 14therebetween but allow the fluorscope attachment 10 to slidably movelongitudinally relative to the image intensifier.

The struts 50 are fixedly attached to the back wall 36 and reinforcingmembers 52 are provided at the ends 51 of each strut connected to theback wall to maintain the perpendicular relationship between the backwall and the struts. As such, the struts hold the holder 24 and hencethe film cassette 28 properly oriented with respect to the x-ray beam.Moreover, no fixed attachment to the image intensifier is required andthe waterproof outer housing of the image intensifier need not bepierced. Since the front and back walls 34 and 36 are x-ray transparent,and the holder 24 does not otherwise affect the functioning of theintensifier, the intensifier may be easily and quickly utilized in aconventional fashion without removal of the attachment 10 if only thefilm cassette 28 and grid 26 are removed from the holder 24.

Three straps 54 have their one end fixedly connected to one of thestruts at three distant positions. The straps may be wrapped around theoutsides of the struts 50 after the image intensifier 14 has been placedwithin the space define by the struts. Velcro™ strips 55 are provided onthe outer side of the strap ends connected to each strut. This allowsthe straps to be wrapped around the struts to slidably secure the strutsto the outer housing 12 of the image intensifier 14 and to interconnectthe struts to maintain their circumferential position about the housing.The strap can be tightened as desired to vary the degree of ease withwhich the struts can slidably move relative to the outer housing.

The image intensifier shown has a forwardly head portion 56 whichprojects forward from the outer housing 12 of the intensifier. When theimage intensifier is used without the fluoroscope attachment 10, theimage intensifier is moved toward the patient to place the head portion56 into contact with the abdomen of a patient in the water bath by amotor (not shown). A pressure sensor internal to the head portiondetects contact of the head portion with the patient's abdomen, and aswitch operatively connected to the pressure sensor stops the motor whenthe contact pressure achieves a predetermined value. With the presentinvention, the strut and strap arrangement allows the fluorscopeattachment 10 to slidably engage the outer housing 12 so that the holder24 will not prevent operatoin of the pressure sensor as the imageintensifier is moved to position the holder 24 at the abdomen of thepatient. In this way the pressure sensor and switch within the headportion remain operative while the attachment is on the outer housing12. That is, when the attachment comes into contact with the patient'sabdomen with sufficient contact pressure the motor drive for the imageintensifier will stop.

An inflatable bladder 60 is attached to the front wall 34 of the holder24 by fasteners 62. Any suitable method may, of course, be chosen forattaching the bladder 60 to the front wall of the holder. The bladderpreferably covers an area sufficiently large that when inflated andpositioned against the patient the x-rays necessary to expose the filmin the film cassette, which is held in the film receptacle 32, will nothave to pass through the water bath where high absorption and scatteringoccur. Rather, the water is displaced by the inflated bladder and thex-rays pass through the inflated bladder with minimal absorption orscattering resulting. The bladder is inflated prior to an exposure ofthe film after the holder 24 has been moved into close proximity to thepatient's abdomen. Conventional air tubes 64 are provided to allowinflation and deflation of the bladder. Two tubes 64 may be provided asshown for inflating and deflating the bladder, or a single tube may beused provided appropriate check valves are incorporated in the tubing.

The bladder 60 is inflated to displace water from the area between thefront wall of the holder 24 and abdomen of the patient. The bladder isflexible to conform to the irregular shapes of patient's abdomen areasinto which it contacts to more fully displace the water. It is wellknown that water tends to absorb and scatter x-rays which would bedetrimental to the formation of a high resolution x-ray film. The meansfor inflating an deflating the bladder are not shown but may include anyconventional means such that used with conventional sphgmomanometercuffs. In a preliminary embodiment it was found that the inflatablerubber balloon from a large sphgomomanometer was effective for use asthe inflatable bladder 60.

When it is desired to more precisely locate the position of fragmentedcalculi in the kidneys or other abdominal region, the followingprocedure is followed. The head struts 50 of the attachment are slidablysecured to the outer housing 12 by appropriate tensioning of the straps54. The image intensifier 14 is then moved toward the patient until theholder 24 is positioned adjacent to the the abdomen of a patient in thewater bath. It is noted that if the motor drive causes the imageintensifier to push the holder 24 too hard against the patient, the backwall 36 of the holder will bear on the internal pressure sensor withsufficient force to switch off the motor since the struts 50 allow thefluoroscope attachment 10 to slide rearwardly.

The inflatable bladder 60 is then inflated to displace water from thearea between the front wall 34 of the holder and the abdomen. When usedwith the Dornier ESWL device the integral x-ray portion (manufactured byPhilip Co.) is adjusted for an x-ray exposure. This is done by turningoff the image storage selectors in the image intensifier portion 14 andinitiating an x-ray exposure technique by depressing thekilovolt-miliamperes button on the x-ray control panel. The kilovolt andmiliampere settings can then be adjusted and the exposure made bydepressing the exposure release button on the control handle. For anaverage size patient a setting of 65 kilovolts and 50 miliamperes isselected when using a grid and film cassette of the type previouslydescribed.

The correct inflation of the inflatable bladder 60 to displace all wateris important to obtaining an x-ray film with maximum resolution. Withthinner patients this is especially a problem since there tends to belarge gaps between the substantially planar front wall 34 of the holder24 and the curved surface of the abdomen. To the extent that water isnot displaced from the space between the front wall in the abdomen areduction in image resolution will occur. With heavier patients theproblem does not tend to be as acute, however, care should nonethelessbe used to insure that the bladder is sufficiently inflated.

In the preferred embodiment the holder 24 has a vertical height ofapproximately 18 inches and a horizontal width of approximately 11inches. The outside depth dimension of the holder and therefore thesidewalls, and bottom is approximately 2 inches. The film receptacle 32,defined by the back wall and projection 48, has a width of approximately5/8 of an inch to slidably accept a film cassette 28 of the typedescribed. The grid receptacle 30 is positioned forwardly of the filmreceptacle and held separated therefrom by the projection 48 and has apreferred width of approximately 1/8 of an inch to slidably receive agrid 26 of the type described. The struts 50 have a length ofapproximately 19 inches.

As will be readily apparent to one skilled in the art, the dimensionscited above are illustrative of a preferred embodiment only and may bevaried so long as the primary functions of the various parts of thefluoroscope attachment 10 are not impaired. For example, the struts 50may be lengthened or shortened according to the dimensions of the imageintensifier upon which the attachment is to be mounted. Furthermore,four or more struts may be provided instead of the three specified inthe preferred embodiment. Further yet, the struts may be altogethersubstituted for by a more dedicated structure which more closelycorresponds to the structure of the image intensifier housing 12. Othermeans for mounting the holder 24 to the image intensifier 14 which donot include the use of struts are considered to be part of theinvention. Specifically, clamps with extending members or dedicatedhousings adapted to receive the outer portion of the image intensifierare contemplated.

Therefore, the scope of the invention is not to be limited by the abovedescription but it is to be determined by the claims which follow.

We claim:
 1. A fluoroscope attachment for holding a grid and filmcassette for filming of a patient exposed to an x-ray beam generated byan x-ray source and received by a fluoroscope image intensifier drivenby a motor drive, the image intensifier having pressure sensing means tostop the motor drive and an outer housing, and the attachment beingusable during extracorporeal shock wave lithotripsy, comprising:a holderhaving a substantially x-ray transparent front wall and a back wallspaced rearwardly from the front wall and having two sidewalls and abottom connected to the front and back walls so as to form a receptaclewith an open top to accept a film cassette and a grid, wherein thesidewalls have means for holding the film cassette and the grid in aspaced parallel relation within the receptacle; and means for slidablymounting the holder to the outer housing of the image intensifier with afilm cassette and grid positionable in the holder being heldsubstantially perpendicular to the x-ray beam incident on the imageintensifier and with the holder being movable with the image intensifierinto contact with the patient to produce a contact pressure therewithand under the resulting contact pressure being slidable on the imageintensifier to allow the back wall to transfer force to the intensifierpressure sensing means to stop the motor drive.
 2. The attachment ofclaim 1 wherein the mounting means comprise a plurality of attachmentmembers rearwardly extending from and attached to the holder andoriented to hold the film cassette in the holder substantiallyperpendicular to the x-ray beam, the members being spaced apart toslidably receive therebetween and frictionally engage the outer housingof the fluoroscope image intensifier.
 3. The attachment of claim 2wherein the members are in frictional sliding engagement with the outerhousing and the attachment further includes means for tightening themembers against the outer housing of the fluoroscope image intensifierto adjust the frictional sliding engagement of the members with theouter housing and for maintaining the relative positions of the memberson the outer housing.
 4. The attachment of claim 3 wherein the membersinclude at least three elongated struts and the tightening meanscomprises straps transversely extendable about the struts and connectedto at least one strut.
 5. The attachment of claim 2 wherein the backwall is parallel to the front wall and the attachment further includesmeans for reinforcing the attachment of the members to the back wall tomaintain the perpendicular position of a film cassette in the holder tothe x-ray beam.
 6. A device for filming of a patient during fluoroscopicmonitoring in extracorporeal shock wave lithotripsy, comprising:an x-raysource capable of generating an x-ray beam; a fluoroscope imageintensifier driven by a motor drive to move the image intensifier towardthe patient; a pressure sensing means mounted on the image intensifierto stop the motor drive upon reaching a predetermined contact pressurewith the patient; a film holder having an opening for removablyreceiving a film cassette therethrough, and means for holding the filmcassette therein; and means for movably mounting the holder to thefluoroscope image intensifier in position between the image intensifierand the patient with a film cassette in the holder being orientedsubstantially perpendicular to the x-ray beam, the holder being movablerelative to the image intensifier and engageable with the pressuresensing means to transfer force to the pressure sensing means upon thedrive motor moving the image intensifier into position with the holderpressed against the patient.
 7. The device of claim 6 wherein themounting means slidably engages the image intensifier so that patientcontact pressure on the holder causes the holder to slide relative tothe image intensifier and transfers a force through the holder to theimage intensifier pressure sensing means.
 8. A method for filming apatient during extracorporeal shock waive lithotripsy using an x-raysource to generate an x-ray beam and a fluoroscope image intensifiermovable toward the patient by a drive means having an associatedpressure sensing means to stop operation of the drive means and movementof the image intensifier toward the patient upon reaching apredetermined contact pressure with the patient, comprising thefollowing steps:placing a film cassette in a holder; slidably mountingthe holder to the fluoroscope image intensifier with the film cassetteoriented substantially perpendicular to the x-ray beam generated by thex-ray source, and with the holder positioned to contact the patient whenthe image intensifier is moved toward the patient and to engage thepressure sensing means stopping operation of the drive means upon thepredetermined contact pressure with the patient being reached;activating the drive means to move the image intensifier toward thepatient with the holder positioned in contact with the patient, with thepressure sensing means of the image intensifier stopping operation ofthe drive means should the predetermined contact pressure with thepatient be reached; and exposing the film cassette with the x-ray sourceso as to pass the x-ray beam through the patient and the holder and ontothe film cassette contained in the holder.